The Division of Comparative Pathology provides anatomic and clinical pathology services to the various Divisions of the Center, affiliated scientists, collaborative scientists and other scientific investigators from the New England area who utilize the resources of this Center. The number of requisitions for these services can be categorized as follows a. Number of post-mortem examinations performed 365 b. Number of biopsy specimens processed and examined 339 c. Number of complete blood counts (CBCs) 3451 d. Number of other clinical pathology requisitions including fecal examinations, chemistry analyses, urinalyses, cytological examinations, and fluid analyses 636 e. Number of specimens collected for outside investigators 90 Complete postmortem and histopathologic examinations were performed on all nonhuman primates that died at the Center including abortuses and stillbirths from the several breeding colonies, animals dying of spontaneous disease while not involved in a research project, and those animals that died or were sacrificed while on specific studies. The data generated from examination of those tissues is used to monitor outbreaks of infectious diseases in our colony, to provide ancillary support for ongoing research studies, and to provide diagnostic support to our clinical veterinary staff. Finally, the diagnostic laboratory is fundamental in the recognition of certain natural diseases of captive nonhuman primates that may be explored as models of certain human diseases states. Examples of these recognized and characterized previously at the Center include simian AIDS, colitis and colonic carcinoma, and glomerulonephritis. Very active and large studies on the pathogenesis of AIDS are ongoing at the present time within the Division of Comparative Pathology, resulting from these initial observations and descriptions. Further characterization of more recently described conditions of nonhuman primates are under investigation, including a bleeding diathesis of Callithrix with concurrent malabsorption and osteoporosis, and arteriopathy in SIV-infected Macaca mulatta.